Step 1

Preheat the oven to 400°F. Line a baking sheet with parchment paper.

Step 2

In a large mixing bowl, combine the flour, granulated and light brown sugars, baking powder, baking soda, and salt. Using a pastry cutter, cut in the cold butter until the pieces are no larger than the size of peas. Toss in the chocolate chips.

Step 3

In a small bowl whisk together ¾ cup heavy cream, egg, and vanilla. Slowly add the cream mixture, using the pastry cutter to mix until a shaggy dough forms. Turn out the dough onto a lightly floured surface and press into a ¾-inch thick square. Cut the dough in half. Stack each half and press down. Repeat the cutting and stacking, then shape into a 7-inch disc. Using a floured knife, cut the disc into 8 equal triangles and place on the prepared baking sheet about 2 inches apart. Sprinkle the tops with additional chocolate chips, if desired. Refrigerate for 15 minutes.

Step 4

Brush scones with the remaining 1 tablespoon of heavy cream and sprinkle with turbinado sugar.

Step 5

Bake for 10 to 12 minutes or until puffed and the tops are lightly golden, rotating the baking sheet halfway through baking. Cool for at least 10 minutes before serving. Scones can be stored in an airtight container at room temperature for up to 4 days, or frozen for 2 months.